Self-consistency constraints on the dynamo mechanism

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Abstract

It is shown that the requirements of self-consistency constrain the functional form of the turbulent dynamo field in an incompressible plasma. These requirements involve the back-reaction of the magnetic field through the Lorentz force in the momentum equation and the conservation laws of magnetohydrodynamic turbulence. The dynamo field is calculated in the weak-field limit when the turbulence is isotropic, as well as in the strong-field limit when the turbulence is anisotropic. For magnetic fields of a nontrivial topology, it is shown that the results of kinematic dynamo theory are strongly modified by the production of hyperresistivity (in the mean-field induction equation) which is left as a remnant after a near-cancellation between the alpha and beta effects. An interpolation formula for alpha quenching, encompassing weak-field and strong-field regimes, is proposed.

Original languageEnglish (US)
Pages (from-to)739-744
Number of pages6
JournalAstrophysical Journal
Volume449
Issue number2
DOIs
StatePublished - Aug 20 1995
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • MHD
  • Plasmas
  • Turbulence

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